Chromosomal investigations in patients with mental retardation and/or congenital malformations

Abstract

We investigated the chromosomal constitution of patients with mental retardation and/or congenital malformations in order to determine genetic causes for such disturbances. The GTG and CBG banding patterns were studied using phytohemagglutinin M-stimulated lymphocytes cultured from peripheral blood. Among 98 individuals with mental retardation and/or congenital malformations who were analyzed there were 12 cases of Down's syndrome, two of Edward's syndrome, one of Patau's syndrome, five of Turner's syndrome, two of Klinefelter's syndrome, one of "cri-du-chat" syndrome, one case of a balanced translocation between chromosomes 13 and 14, one case of a derivative chromosome and one of a marker chromosome. We found abnormal chromosomes in 26% of the patients, 82% of which were numerical abnormalities, with the remaining 18% being structural variants. We conclude that patients with mental retardation and/or congenital malformations should be routinely karyotyped.

Cytogenetic analysis of chromosomal abnormalities in Sri Lankan children

“…This indicates early referral by the investigating clinicians for chromosomal analysis which may have resulted from a high index of clinical suspicion as well as from the increased awareness among clinicians about cytogenetic analysis. In agreement with several previous studies, [3,9,11,14,16,18] chromosomal non-disjunction was the main cause of DS with 84.2% of the children having free trisomy 21. DS due to mosaicism (10.8%) was found to be higher than due to Robertsonian translocations between chromosome 21 and the acrocentric chromosomes (5.0%).…”

“…Other reasons for the difference in prevalence reported in these studies may be due to the varied inclusion criteria of patients, the cytogenetic methods used and the discordance of classification criteria. [5] Both adults and children were included in other studies [3,5,9,[12][13][14] and only few were conducted exclusively among children suspected of chromosomal disorders. [15,16] The majority of chromosomal abnormalities observed in this study were numerical abnormalities (45.9%).…”

“…It is interesting to note that the cytogenetic pattern of DS is variable among different studies. [9,14,16,18,19] It is difficult to identify the reasons for these discrepancies but could be due to the variations in the selected study populations. Identification of translocation DS in the fetus or newborn is an indication for karyotypic analysis of both parents as either of them may be carriers of a balanced translocation involving chromosome 21.…”

Cytogenetic analysis of 4216 patients referred for suspected chromosomal abnormalities in Southeast Turkey

“…The frequency of chromosomal anomalies was considerably higher than that related to an unselected population (0.5-0.6%) (Hamerton et al, 1975;Hook and Hamerton, 1977;Patil et al, 1977), and it was also higher than the 6.3% by Solak et al (2007), while it was similar to 14.3% by Butler and Hamill (1995) and the 13.4% by Al Husain and Zaki (1999), and smaller than the 21.6% found by Milia et al (1984), the 27.2% found by Verma and Dosik (1980), 28.6% by Santos et al (2000), and 29.3% by Duarte et al (2004). The differences in the frequencies of the chromosomal abnormalities among these studies could explain increased interest in genetic diseases by physicians and reflect variations in criteria for inclusion of the patients and the cytogenetic methods used and discordance of classification criteria (Kim et al, 1999).…”

Profile of Patients Attended at the Genetic Service of a Special Care Institution in Brazil

“…In other studies carried out in different genetic centers in the country, prevalence rates of between 15% and 29% of chromosomal aberrations among the investigated patients were also observed [2,11,15,[22][23][24][25]. It should be highlighted that most of the patients attended came from the APAE/Manaus causing a possible bias in the sample.…”